Lifting jack



ug. 2l, 1923. l,4f65,570

- E. E. ARNOLD LIFTING JACK Filed May 29, 1920 2 Sheets-sheet@ Patented Aug. 2l, 1923.

Y VJNT YSV EDWIN n. ARNOLD', lon rirrsnun'en,

rss:

rnonuo'rs COMPANY, ii` oonroniirion or rnNNsYnvANIA.

` iarriNG JACK.' Y

Application sieri may es',`

new and usefulV Invention in Lifting Jacks,

of which the following is a specification.

This invention relates to lifting jacis and has for an objectto produce a heavy duty' Vjack which iscompact, relatively light,-

s'imple to manufacture and simple and ef-V fective in operation. and which includes a double Worin drive as apart Of the operating mechanism. f

A further object is to produce a `YWorm actuated jack of large capacity in which the load to which the lifting mechanism is sub- `iected is distributed between two ivorm gear trains which form afpart of the operating mechanism, These and other objects which will he made more'apparent throughout the further description of the inventioni'are at-v tained by means of a jack embodying the features herein described and illustrated in the drawings 'accompanying and forming a part hereof. In the drawings .Figurefi is a sectional view talreiialong the line l-l of Figure 2 and .illustrates a'jacl; embodying my invention. VlFigureZ is a sectional` view tal-ren along the line 2 2 of-Figure l.- Figure 3 is a sectional view taken along theA line 8 3 of Figure l and. .Figure t is a sectional view taken along the line 1 -'t of Figure 3.

Lifting jacks employing double. Worm gear Operating mechanisinsliave many advantages over ordinary .ia-chs, primarily be cause the load yto which the lifting rain and the operating mechanisml is subiect'ed is distributed over tryo sets of.OperatingV gears.l

Double Worin jacks as ordinarilyconstruct: f ed are.V however, iiot'ivell adapted for large In tlief ilustrated embodi ment this is accomplished by employing aV screw actuated ram and an operating mecha;

192e. seriai'N-o. 385,302.

nism for the lscrew including'twoY interineshing spiral gears which are actuated by means of right and left hand "Worm,

erniiiisrnvenia, iassrsNon .ro inoN CITY .Y Y'

through the'agency ofivorm engaging teethV g formed on.' each gear.

by Worms' formed Ontlie saineivorin shaft,

it is essential to so construct the Worm path or Worm engaging teeth: co-Operatiiig with each gearth'at eachV Worm Yafi-ll take its prolnasinuc'h as the Yspiral gears Viiit'eriiiesh and are also Ydriven portion of thev load and will transmit fits" it is necessary to maintain a three Vpoint contaet,1and to maintain it in such awaythat bodiment by forming Worin path on, the spiral gears in suchv away that! the Worm engaging teeth of each gear have the same nominaljpitch and spiral angularity as the` teeth of the spiral gears, and by so mounting` the right and left hand Worin. *that it .each contact transmits its proportion of the ,power applied. to vthe rain orvtales vits proportion of the load. This is'easily and simply accomplished in the illusti-'ated ern-r` is xfree to move axially, to automatically 'equalizethe power transmitted by the right and left hand portions of the Worm. Vlilith such an arrangement it is arelatively simple 'Y problem to manufacture a, powen traiisinhV co-operating- Yworin path are maintained durall OperatingV conditions ofV the jack. Referring to the drawings; the jack illustrated is provided Witha base 5 whichV sup'` ports the operating` mechanismf and theA Weight of theV liftinpg'rain 6. and Which also meshing ivithithe threads Of a steep pitch screw 8 which entends into the Vrain andis ftinggear train in which the Yproper gear f contactbetiveen the teeth ofthe spiral gears and betweenfeachWorm and-the teeth of its supports the housing and ram guide 7. VThe ram maybe tubular in "formand as. shown is provided. with Vinternal threadsA preferablysupported by afthrust'lcollar 9. f

The thrust collar 9 is in turn supported bv thrust bearing 10 mounted on the 'hase Thethrust bearing illustrated is of the ball type, but obviously anytype of thrust bearingV be employed. 3

As shown, a combinationworm Wheel and spiral gearlljis keyed or Otherwise rigidly 12. The combination spiral gear and worm.

wheel 12 is journaled on a vertical shaft 12a which is suitably mounted on the base 5'.y

The axis of the. gear 12 is parallel to the aXis of the gear 11, and the axes of both these gears extend at right angles to the ,axis ot the worm shaft 14.

The worm shaft 14; is journaled in suitable bearings formed in the jack housing and is so arranged that it is 'free to move axially an amount sufficient to insure autoliatic equalization of the load on the two parts of the worm. A bevel gear 16 is so mounted on the shaft 141; that it accommodates the longitudinal motion of the shaft but at the same time is capable yof transmitting rotary motion to it. This may be accomplished by splining the gear to the shaft.. The gear 15 meshes with a bevelvgear 17, mounted on a shaft 18, which isL suitably joui'naled in the jack housing. .ln the illus.k

ti'ated embodiment, a ratchet mechanism 19 is mounted on the projecting end of the shaft 18 and is adapted to impart rotation to the worm .11i in a direction to lift the rain 6.Y rfhe ratchet mechanism is preferably adapted to impart motion in one directiony only to the shaft 18 and consequently the jack is provided with a lowering crank 20v which is operatively connected to a shaft 20.1suitably jouinaled in the housing 7 and carrying a gear As shown,` this gear meshes with crown teeth 22 formed on the bevel gear 16. f

its has been stated the worm path on each gear 11. and 12 is formed integrally with the gear. is illustrated each worm path is lo-r cated midway between the ends of its associated gear, and each worin engaging tooth, forming a `pai-t of the path` is, in effect, a the spiral teethv of the continuation of one. i: gear. Each gea is so proportioned that ample normal tooth surface is provided on either side of the worin pathy to insure proper operation of the'gears.

In manufacturing these combination gear and worin wheels the spiral teeth a e formed in the usual maniier. The worm path is then piel. .fably so Aformed on, each gear that the nominal pitch and spiral aiigularity of the worm engaging teeth are the same as the Aspiral teeth of the gear. Each worm path is, however. formed by a hob capable of cutting a replica of the path engaging worm. It is necessary or at least desirable to cut the worin path to a sub-pitch diameter with relation to thezpitch diameter of the gear teeth so as to give ysufficient surface contact for good working conditions and adequate lubrication of the worin. T his may be accomplished by allowing the worm path hob to run in slightly beyond the normal pitch diameter suchfangularity as to allow it to be'revolved by the pressure of the'load upon the ram.y i The operating gear train is, however, prete erably so designed, that it is'not reversible under load, but the angle ofthe worm teeth is preferably such that a relatively small turning force applied, for example, tol the crank 20, will overcome the friction between.

the worm and worm engaging teethv and permit the load to be lowered quickly or thevv jack to be quickly adjusted by the'crank 2Q; Q0

The jack is placed in position and the u crank 20 is employed to adjust the ram to a 1 The operation ofthe jack is as follows:

lifting position with relation tothe load to I be lifted. the ordinary manner and during the operation ofthe jack both worms' 13-15 are effective in transmitting Apower to the ram, be-

cause of they oating of the worm and the"V consequent automatic ad]ustment for the purpose of equalizing the work done by each worm. The worm shaft 14 transmits equal.

operating forces to the `worm paths formed on the gears 11 and 12 and the force transmitted -tothe gear 12'isftransmitted rby means of the intermeshing gear 11 to -the screw 8. Substantially'all the power applied to the worm shaft visemployed in doing effective work in raising the ram, since there arefnounbalanced axial thrusts occasioned within the operating mechanism, and

Consequently the tooth pressure is-relatively The ratchet is then employed. inv

low, with reference to thel load encounteredy f by the ram and there lis no necessity for em-4 ploying restraining or counter-balancing thrust bearings in the operating inechanisiir The thrust imparted by the load is borne entirelyby the thrust bearing 10. ln addi ins. Y

tion to the automatic equalization of the f load on, yor the delivery of power by the two worms 13 and 15, the longitudinally.v Heating-'1 worm shaft, is capable of compensatinglfor slight inaccuracies in theformation'of the teeth and will continually-adjust itself to Y' equalize the load under all varying operat ing conditions encountered. y

As has been described,the angular pitch yof the screw 8 is such vthat it is reversible under load, whereas the angular pitch of the worms is, such as to just prevent such a reversal under ynormal load conditions.

For'

this reason the crank 20 may be readily em-` ployed in lowering the load and in moving the rain into or out of contact with the load.

In the drawings I have shown lthe jack lubricant, such as oil, the shaft 18 will preferably be provided with a packing at the joint between it and the housing. If the lubricant level isv located above the axisof the worm shaft it will also be desirable to pack thejoint between the housing and the shaft 20 or the appurtenant crank- 20.

It will be apparent that the combination gear and worinwheel members 11 and 12 may be of different pitch diameters and that various changes, additions and omissions may be made in the details of construction of the jack illustrated without departing from the spirit and scope of my invention as set forth. by the appended claims.V

What I claim is:v

1. In a jack, a ram, in combination with an operating mechanism therefore, comprising two intermeshing spiralgears, worin ening with the worm engaging teeth of eachoear. Y C 3. In combination in a jack, a ram, and an operating mechanism therefore, comprising two intermeshing spiral gears, a worm path of ,substantially `the same nominal pitch and spiral angularity as the teeth of said gears hobbed to a sub-pitch diameter on each gear, a right and left hand worin engaging the worin path of both gears, and means secured to one of said gears for actuating said ram.

4. In combination in a jack, a ram, and an operating mechanism therefore, comp-rising a right and left hand worm, intermeshiiig gears, a worm path hobbed in each gear and a screwjaclr, a. ram,

a screw for actuating said ram, aV worm wheel for actuating the screw, a worm for actuating the worm wheel, a ratchet, bevel gears for imparting motionof the ratchet to the worm, a crown gear formed on one of said bevel-gears and meshing therewith for actuating said worm independently of said ratchet. f

V6. In a jacln'a lifting ram, in combination with a ram Vactuating mechanism therefore, including two worin wheels,means for gearing said worin wheels together, a compound. worm meshing with both worm wheels and movable axially to equalize tooth pressures between the worm and each worin wheel, and means for transmitting power from said worm wheels tosaid lifting rams.v Y v 7. In a ack, a lifting ram, in combination with a rain actuating mechanism therefore, including two worm wheels, means for gearing said wheels together, va right and left hand worm meshing with said worin wheels Vand movablerelatively to the axis of one worm wheel to automatically equalize the power transmitted by the worm to each wheel and means for transmitting power from the-worm wheelsto the ram.

8. In a ack, a lifting ram and an operatf ing mechanism therefore, including ,two interineshing spiral gears, a worm path of vsubstanti ally the same nominal pitch and spiral angularity hobbed to a sub-pitch diameter on each' gear, a right and left hand self adjusting worin engaging the worm path of both gears, means for transmitting power to said worm and means for transmitting power from said gears to said ram.

Y 9- In combination in a lifting jack, a ram, an operating mechanism therefor comprising twoY intermeshing gears, a worm path formed on each gear, a right and left hand worm meshing with both. wormfpaths andi movable axially to equalize tooth Vpressure between the worm and each worm path, a `ratchet mechanism and means including al gear mounted on said wormrand movableY longitudinally with relation thereto for imparting motion fromV the ratchet to said worm, a ram-engaging screw mounted onv gears, and a one of the first-mentioned thrustbearing for said gear.

In testimony whereof, I have hereunto subscribed myname this 278th day of May, 1920. f

EDWIN n. ARNOLD. 

